Then shod those rims in a 4.00x18 or 110/90-18 rear tire and a 90/90-19 or 100/90-19 front tire. PirellI Sport Demons for the ULTIMATE grip.
Bridgestone Battlax BT-45 for similar grip but slightly longer life on the rear tire if you ride straight flat roads primarily.
Shinko 230 TourMaster front if on a budget and wanting ultimate grip.
Avon AM26 RoadRiders if you do a lot of straight road riding and load on lots of long miles.